Yarn feeder and changer unit

ABSTRACT

A yarn feeder and changer unit for a knitting machine comprises a number of adjacent yarn feeders any one of which can be moved from a yarn trapping position to a yarn feeding position while the others retain severed ends of their respective yarns at the trapping positions. The movement of each feeder to its feeding position comprises an upward component of movement from below the needle level by pivotal movement about a horizontal axis, and forward movement over the needles by a sliding component of movement. The creation of two distinct components of movement for each feeder (pivotal and sliding) enables the feeder path to pass close to but out of the path of the needles, and enables accurate yarn placement to be achieved.

DESCRIPTION

This invention relates to yarn feeder and changer units, otherwise known as striper units, for knitting machines. In such units any of a number of adjacent yarn feeders can be moved from a stowed position adjacent a yarn cutter and trapper mechanism to a yarn feeding position. In the stowed position when the yarn is cut and the severed end trapped at a level below that of the knitting needles, the greatest degree of yarn control is achieved by having the yarn feeder at that same low level, with the minimum length of yarn between the feeder and trapper. Direct movement of the yarn feeder in a straight line from its trapping position to its yarn feeding position would take the feeder into the path of the needles, which would cause damage.

Prior proposals have therefore provided complex and cumbersome striper mechanisms to place the yarn in the correct feeding position. One prior proposal is that of British Patent Specification No. 821,151 which utilizes feeders pivotable about a first axis, each feeder having an associated yarn placer pivotable about a second axis above and in front of the first axis. Feeder movement is purely pivotal and raises the yarn guide eye of the feeder from the trapping position to above the needle level. Movement of the yarn placement point forwardly over the needles is achieved by pivotal movement of the placer. This prior proposal utilizes two independently movable and independently spring-loaded elements for each yarn to be fed, namely a feeder and a placer.

The need for a separate yarn placer was avoided in British Pat. No. 1,556,659 by lifting each yarn feeder from a suspension point above the needle level and effecting forward movement of a yarn guide eye of the feeder at an appropriate stage during the lifting by means of a fixed pin engaging a Z-shaped cam track in the feeder. This solution is effective, but imparts design limitations. There is always an upward component of feeder movement, as the movement is generated by lifting the feeder at its suspension point. Much of the structure is necessarily above and immediately in front of the needles so that inspection and access is difficult when the unit is installed on the knitting machine. Finally, separate striper cam plates are required for actuating the feeders and the associated yarn cutting and trapping mechanisms, which is an undesirable expense.

This invention provides a yarn feeder and changer unit for a knitting machine comprising a number of yarn feeders each movable between yarn feeding and yarn trapping positions, wherein movement of each feeder from its yarn trapping position to its yarn feeding position is a combination of forward sliding movement and pivotal movement about an axis perpendicular to the direction or plane of sliding, in response to forward sliding movement of an associated actuator slide.

It is an object of the invention to achieve such feeder movement with the feeders mounted in side-by-side relationship on a pair of fixed mounting pins, to achieve maximum precision of feeder movement which is in two separate and defined successive movements from the yarn trapping feeder position to the yarn feeding feeder position.

By combining pivotal and forward sliding movement of the yarn feeders a substantial flexibility of design can be achieved, with the feeder movement upwards from below the needle level being essentially a consequence of the pivotal component of movement and the feeder movement forwards over the needles being essentially a consequence of the sliding component of feeder movement.

Although a simple and therefore often preferred sequence of feeder movement involves these two components of feeder movement as two separate and successive movements of the yarn guide eyes of the feeders, it is possible according to the invention to combine the two components of movement as desired to cause the yarn guide eye to traverse a wide variety of paths from its yarn trapping position to its yarn feeding position.

One of the components of feeder movement is preferably cam actuated. For example the pivotal movement may be in response to cam action of the actuator slide on the feeder, while the sliding movement of the feeder is movement of the actuator slide and feeder together and in the same direction. Each feeder is slidably and pivotally mounted on first and second spaced fixed pins, and each feeder may have a camway cooperating with an associated lever plate that is pivotally mounted on the first pin. In such a construction the feeder movement may comprise actuating movement of each lever plate in response to forward movement of its associated actuator slide causing its feeder to move from its yarn trapping position to its yarn feeding position by a combination of pivotal movement, together with the lever plate, about the first pin and forward sliding movement, relative to the lever plate, over the first and second pins under the cam action of the lever plate.

The invention is illustrated by the drawings, of which:

FIGS. 1 to 4 are vertical sections through a yarn feeder and changer unit according to the invention at four consecutive stages of advancement of a yarn feeder from a trapping position (FIG. 1) to a yarn feeding position (FIG. 4). FIG. 2 includes additional detail necessary for a complete understanding of the unit but this detail has not been repeated in FIGS. 1, 3 and 4;

FIG. 5 is an end elevation of the unit of FIGS. 1 to 4 in the direction of the arrow V (FIG. 2);

FIG. 6 is an end elevation of the unit of FIGS. 1 to 4 in the direction of the arrow VI (FIG. 1); and

FIG. 7 is a plan view of a striper cam plate of a knitting machine for use with the unit of FIGS. 1 to 6.

FIG. 2 depicts a part of a needle cylinder 2 of a knitting machine, in which needle cylinder are formed tricks 4 in which cylinder needles 6 are reciprocably movable. Other needles 92 are dial needles movable in a dial (not shown) of the knitting machine.

The yarn feeder and changer unit of FIGS. 1 to 6 comprises a housing or fixed support frame, formed by side plates 10 spaced apart by a cover 12 and by mounting blocks 14 and 16 in which are formed slideways 18 and 20 for an array of four actuator slides 22, 24, 26 and 28. The actuator slides 22, 24, 26 and 28 have actuating butts 23, 25, 27 and 29 respectively at different operating heights to that movement of the unit past a stationary striper cam plate 30 in the direction of the arrow C as illustrated in FIG. 7 actuates a selected one of the actuator slides, the selection depending on the height of the plate 30.

A forwardly facing nose 32 of each actuator slide engages a depending tail 34 of an associated lever plate 36 which is pivotally mounted on a pin 38. A yarn feeder 40 is positioned alongside each lever plate 36 and is slidably and pivotally mounted on the pin 38 and a pin 42 parallel thereto. The pin 38 passes through a slot 44 to the rear of each feeder 40 and the pin 42 passes through an L-shaped slot 46 to the front of each feeder 40.

The L-shaped slot 46 comprises a first branch that is generally arcuate about the forward end of the slot 44, and a second branch that extends rearwardly of the first branch. The second branch, which is horizontal, is generally parallel to the slot 44.

A stub shaft 48 extends from each lever plate 36 into a camway 50 in the associated feeder 40, the camway 50 being formed as a continuation of, and inclined relative to, the generally horizontal portion of the L-shaped slot 46. A compression spring 52 on a spring retainer 54 urges each lever plate 36 anticlockwise about the pin 38 to maintain the tail 34 in contact with the nose 32 of the associated actuator slide. The spring 52 is under compression between a saddle portion 56 of each retainer 54 and the cover 12, with rod portions 58 of the retainers 54 passing through apertures in the cover 12.

An actuator latch 60 is provided for each actuator slide to retain the actuator slide in a forward position even after the striper cam plate 30 releases the actuating butt of the slide. The latches 60 are biased anticlockwise to the latching condition shown in chain-dotted lines in FIG. 2 by springs 62. In the latching condition the latches 60 engage shoulders 63 of the actuator slides, and they can be released by moving the entire unit past a cam (not shown) immediately before the striper cam plate 30.

The unit also comprises a cutter and trapper mechanism 64 including a yarn cutter and trapper assembly for each of the four feeders 40. Each yarn cutter and trapper assembly comprises a fixed cutter blade 66, a moving cutter blade 68 and a trapper 70, as clearly shown when FIG. 6 is considered in conjunction with FIG. 2. Anticlockwise movement of the moving cutter blade 68 from the yarn releasing position shown in chain-dot lines in FIG. 2 to the yarn trapping position shown in solid lines causes first the trapping of a yarn length between the moving cutter blade 68 and the trapper 70 and then the severing of the yarn between the moving cutter blade 68 and the fixed cutter blade 66. Leaf springs 72 are provided resiliently to urge the trappers 70 against the moving cutter blades 68. Each moving cutter blade 68 is biased anticlockwise by a tension spring 74, but can be held in the yarn releasing position by a rotary latch 76 biased to the position shown in solid lines in FIG. 2 by a compression spring 78. Movement of the respective actuator slide fully forward to the position of FIG. 4 causes a tail 80 of a moving cutter blade 68 to move past its rotary latch 76 as shown in FIG. 4, to hold the yarn cutter and trapper open as shown in chain-dot lines in FIG. 2. Release of all the movable cutter blades 68, resulting in trapping and severing of all yarns fed, is achieved by forward movement of a cutter release catch 82 against the bias of a compression spring 84 until it and the rotary latches 76 assume the positions shown in chain-dotted lines in FIG. 2 and the tails 80 of the moving cutters 68 are released. Forward movement of the catch 82 is achieved by moving the entire unit past a stationary cam (not shown).

In use, a different yarn 86 is fed to a yarn guide eye 88 of each of the four feeders. The yarns 86 are passed through forward-opening portions 90 of the eyes 88, so that the leading surface of the feeder pushes each yarn into the path of the knitting needles 92 as shown in FIG. 2. Initially all yarns 86 are trapped between the trappers 70 and their associated moving cutter blades 68, and the feeders 40 and actuator slides are in the positions shown in FIG. 1 in which only the actuator slide 22 is shown for clarity. This corresponds to the butt 23 approaching the striper cam plate 30 of FIG. 7 at the butt level marked D when the actuator slide 22 is fully retracted in its slideways 18 and 20.

Movement of the butt 23 up the striper cam plate 30 to the level marked E in FIG. 7 brings the mechanism to the condition of FIG. 2, with the lever plate 36 and feeder 40 having rotated as a unit about the pin 38. Rotation of the feeder 40 is achieved by the combined effects of the upwardly extending branch of the L-shaped slot 46, which prevents sliding of the feeder on its pins 38 and 42, and the stub shaft 48 which can slide in the camway 50 only on sliding movement of the feeder.

Continued forward movement of the actuator slide 22 as the butt 23 rises to level F on the striper cam plate 30 causes forward sliding movement of the feeder 40 on its pins 38 and 42 as the stub shaft 48 traverses the camway 50. This brings the unit to the condition of FIG. 3, with the feeder 40 feeding its yarn to the needles while the yarn end is trapped between the moving cutter blade 68 and the trapper 70 as shown in full lines in FIG. 2. It will be appreciated that at this stage the moving cutter blade is still in its yarn cutting and trapping position.

Further forward movement of the actuator slide 23 up the slope of the striper cam plate 30 to the level G of FIG. 7 causes the moving cutter blade 68 to release the yarn end as shown in FIG. 4. By this stage however the yarn has been caught up in the needles so that yarn feed and knitting continues normally. The forward movement of the actuator slide 22 from the position of FIG. 3 to that of FIG. 4 causes the lever plate 36 to rotate further clockwise against the bias of the spring 52. However this movement does not result in any further movement of the feeder 40 as the stub shaft 48 merely traverses a slot 94 which is an extension of the camway 50 and is arcuate about the pin 38 when that pin is at the rearward end of the slot 44 as in FIGS. 3 and 4. In this way the same actuator slide 22 can be used to achieve consecutive movement of the feeder 40 and the moving cutter blade 68.

The blade 68 is held in the open position by the latch 76 as the butt 23 returns down the striper cam plate 30 to the level H of FIG. 7, and the lever plate 36 and slide 22 return to the positions of FIG. 3. Further retraction of the actuator slide 22, as the butt 23 leaves the striper cam plate 30, is prevented by the latch 60. The feeder 40 and cutter and trapper assembly 64 are therefore maintained in the positions of FIG. 4 until the synchronized release of the latches 60 and 76 at a subsequent yarn selection station immediately following which a striper cam plate 30 at a different butt level actuates another of the actuator slides 24, 26 or 28.

The path of movement of the yarn guide eye 88, 90 of the yarn feeder 40 is a function of the shapes of the L-shaped slot 46, the camway 50 and the slot 44. In the illustrated embodiment the movement comprises two distinct and defined successive components, namely an arcuate pivotal component of movement around the pin 38 followed by a forward sliding movement on the pins 42 and 38. If the upwardly extending portion of the L-shaped slot 46 were anything other than arcuate about the forward end of the slot 44 the initial upward movement of the feeder would be a combination of pivotal movement and forward or rearward sliding movement. If the rearwardly extending portion of the L-shaped slot 46 were parallel to the slot 44 but both slots were inclined upwardly or downwardly, the forward movement of the feeder 40 would be along a similarly inclined path. If the rearwardly extending portion of the L-shaped slot 46 were other than parallel to the slot 44, the forward movement of the feeder 40 would have a pivotal component of movement which could result in upward or downward movement of the yarn guide eye 88, 90. Thus the designer is given sufficient freedom to ensure that the feeder movement is from the optimum yarn trapping position to the optimum yarn feeding position along the optimum path, for any design of knitting machine. 

We claim:
 1. In a knitting machine having a circular array of needles axially reciprocable in tricks in at least one needle cylinder, a yarn feeder and changer unit comprising:a fixed support frame alongside the needle cylinder or cylinders; first and second parallel mounting pins rigidly mounted on said support frame; a number of yarn feeders mounted on the said mounting pins in side-by-side relationship, each having a yarn guide eye and each being movable on the said mounting pins between a first position in which the said yarn guide eye is in a yarn trapping position and a second position in which the said yarn guide eye is in a yarn feeding position, said first mounting pin passing through a first elongate slot in each yarn feeder and said second mounting pin passing through a second elongate slot in each yarn feeder; and actuating means including a linearly reciprocable slide member for each yarn feeder, whereby linear movement of each slide member in an actuating direction causes the associated yarn feeder to move from its first position to its second position in two separate and defined successive movements of which the first is a pivotal movement of the yarn feeder about the said first mounting pin and the second is a sliding movement of the yarn feeder over the said first and second mounting pins, said actuating means for each yarn feeder comprises said slide member and a lever plate, the lever plate being pivotally mounted on said first mounting pin and having cam means engaging the associated yarn feeder, and the slide member bearing on the lever plate so that linear movement of each slide member in the said actuating direction causes a pivotal movement of the associated lever plate and yarn feeder together about said first mounting pin to complete the said first feeder movement, followed by a continued pivotal movement of said lever plate about said first mounting pin to cam the yarn feeder in a sliding movement over said first and second mounting pins to complete the said second feeder movement.
 2. A yarn feeder and changer unit according to claim 1, wherein the second slot of each yarn feeder comprises a first branch that is generally arcuate about a forward end of the first slot, and a second branch that extends rearwardly of the first branch.
 3. A yarn feeder and changer unit according to claim 2, wherein the second branch of the second slot of each yarn feeder is generally parallel to the first slot.
 4. A yarn feeder and changer unit according to claim 1, wherein said cam means on each lever plate comprises a stub shaft on the lever plate engaging a cam slot in the associated feeder for two-way cam movement of the feeder by the lever plate.
 5. A yarn feeder and changer unit according to claim 4, wherein the cam slot in each feeder is a continuation of the second slot.
 6. A yarn feeder and changer unit according to claim 5, wherein the cam slot in each feeder terminates in an arcuate portion centred around a rearward end of the first slot, so that further pivotal movement of the lever plate is permitted when the feeder is in its yarn feeding position, without corresponding movement of the feeder.
 7. A yarn feeder and changer unit according to claim 4, wherein each lever plate has a tail depending into the path of its associated slide member so that forward movement of the slide member effects the pivotal actuating movement of the lever plate.
 8. A yarn feeder and changer unit according to claim 7 wherein each lever plate is spring-biased in a direction opposing its pivotal actuating movement.
 9. A yarn feeder and changer unit according to claim 7 or claim 8, wherein the slide members have operating butts at different heights for actuation by striper plates of the knitting machine.
 10. A yarn feeder and changer unit according to claim 1, further comprising a latch mechanism associated with each slide member for releasably retaining the slide member in a forward actuating position.
 11. A yarn feeder and changer unit according to claim 1, wherein forward movement of each slide member beyond a position necessary to bring its associated feeder into its yarn feeding position effects yarn release movement of a yarn cutter and trapper mechanism for that feeder.
 12. A yarn feeder and changer unit according to claim 11, further comprising a latch mechanism for releasably retaining the yarn cutter and trapper mechanisms in their yarn releasing positions against the bias of spring means. 